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Recursion: compare with iteration on fibonacci algorithm
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.gitignore

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node_modules/

README.md

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- [recursion & iteration](./recursion/recursion.md) (updated 2021-01-11)

package-lock.json

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recursion/fib.ts

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const ORDER = 40
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function fibRecursion(n: number): number {
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if (n === 0) return 0;
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if (n === 1) return 1;
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return fibRecursion(n - 1) + fibRecursion(n - 2);
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}
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console.time('fib')
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const result = fibRecursion(ORDER)
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console.timeEnd('fib')
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console.log(result)
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function fibIteration(n: number): number {
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if (n === 0) return 0
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if (n === 1) return 1
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let pp = 0
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let p = 1
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let result = 0
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for (let i = 2; i<n; i++) {
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result += p + pp
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pp = p
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p = result
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}
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return result
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}
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console.time('fib2')
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const result2 = fibIteration(ORDER)
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console.timeEnd('fib2')
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console.log(result)

recursion/recursion.md

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## iteration & recursion
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- recursion은 iteration에 비해 가독성이 좋지만, 실행 시간이 길다는 단점이 있다.
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- recursion은 함수에 대한 스택메모리가 추가적으로 필요하다.

tsconfig.json

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{
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"compilerOptions": {
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/* Visit https://aka.ms/tsconfig.json to read more about this file */
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/* Projects */
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// "incremental": true, /* Enable incremental compilation */
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// "composite": true, /* Enable constraints that allow a TypeScript project to be used with project references. */
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// "tsBuildInfoFile": "./", /* Specify the folder for .tsbuildinfo incremental compilation files. */
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// "disableSourceOfProjectReferenceRedirect": true, /* Disable preferring source files instead of declaration files when referencing composite projects */
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// "disableSolutionSearching": true, /* Opt a project out of multi-project reference checking when editing. */
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// "disableReferencedProjectLoad": true, /* Reduce the number of projects loaded automatically by TypeScript. */
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/* Language and Environment */
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"target": "es2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
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// "lib": [], /* Specify a set of bundled library declaration files that describe the target runtime environment. */
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// "jsx": "preserve", /* Specify what JSX code is generated. */
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// "experimentalDecorators": true, /* Enable experimental support for TC39 stage 2 draft decorators. */
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// "emitDecoratorMetadata": true, /* Emit design-type metadata for decorated declarations in source files. */
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// "jsxFactory": "", /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
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// "jsxFragmentFactory": "", /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
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// "jsxImportSource": "", /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
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// "reactNamespace": "", /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
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// "noLib": true, /* Disable including any library files, including the default lib.d.ts. */
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// "useDefineForClassFields": true, /* Emit ECMAScript-standard-compliant class fields. */
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/* Modules */
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"module": "commonjs" /* Specify what module code is generated. */,
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// "rootDir": "./", /* Specify the root folder within your source files. */
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// "moduleResolution": "node", /* Specify how TypeScript looks up a file from a given module specifier. */
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// "baseUrl": "./", /* Specify the base directory to resolve non-relative module names. */
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// "paths": {}, /* Specify a set of entries that re-map imports to additional lookup locations. */
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// "rootDirs": [], /* Allow multiple folders to be treated as one when resolving modules. */
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// "typeRoots": [], /* Specify multiple folders that act like `./node_modules/@types`. */
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// "types": [], /* Specify type package names to be included without being referenced in a source file. */
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// "allowUmdGlobalAccess": true, /* Allow accessing UMD globals from modules. */
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// "resolveJsonModule": true, /* Enable importing .json files */
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// "noResolve": true, /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */
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/* JavaScript Support */
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// "allowJs": true, /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */
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// "checkJs": true, /* Enable error reporting in type-checked JavaScript files. */
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// "maxNodeModuleJsDepth": 1, /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */
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/* Emit */
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// "declaration": true, /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
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// "declarationMap": true, /* Create sourcemaps for d.ts files. */
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// "emitDeclarationOnly": true, /* Only output d.ts files and not JavaScript files. */
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// "sourceMap": true, /* Create source map files for emitted JavaScript files. */
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// "outFile": "./", /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
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// "outDir": "./", /* Specify an output folder for all emitted files. */
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// "removeComments": true, /* Disable emitting comments. */
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// "noEmit": true, /* Disable emitting files from a compilation. */
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// "importHelpers": true, /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
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// "importsNotUsedAsValues": "remove", /* Specify emit/checking behavior for imports that are only used for types */
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// "downlevelIteration": true, /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
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// "sourceRoot": "", /* Specify the root path for debuggers to find the reference source code. */
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// "mapRoot": "", /* Specify the location where debugger should locate map files instead of generated locations. */
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// "inlineSourceMap": true, /* Include sourcemap files inside the emitted JavaScript. */
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// "inlineSources": true, /* Include source code in the sourcemaps inside the emitted JavaScript. */
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// "emitBOM": true, /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
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// "newLine": "crlf", /* Set the newline character for emitting files. */
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// "stripInternal": true, /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
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// "noEmitHelpers": true, /* Disable generating custom helper functions like `__extends` in compiled output. */
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// "noEmitOnError": true, /* Disable emitting files if any type checking errors are reported. */
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// "preserveConstEnums": true, /* Disable erasing `const enum` declarations in generated code. */
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// "declarationDir": "./", /* Specify the output directory for generated declaration files. */
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// "preserveValueImports": true, /* Preserve unused imported values in the JavaScript output that would otherwise be removed. */
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/* Interop Constraints */
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// "isolatedModules": true, /* Ensure that each file can be safely transpiled without relying on other imports. */
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// "allowSyntheticDefaultImports": true, /* Allow 'import x from y' when a module doesn't have a default export. */
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"esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */,
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// "preserveSymlinks": true, /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
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"forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,
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/* Type Checking */
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"strict": true /* Enable all strict type-checking options. */,
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// "noImplicitAny": true, /* Enable error reporting for expressions and declarations with an implied `any` type.. */
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// "strictNullChecks": true, /* When type checking, take into account `null` and `undefined`. */
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// "strictFunctionTypes": true, /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
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// "strictBindCallApply": true, /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */
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// "strictPropertyInitialization": true, /* Check for class properties that are declared but not set in the constructor. */
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// "noImplicitThis": true, /* Enable error reporting when `this` is given the type `any`. */
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// "useUnknownInCatchVariables": true, /* Type catch clause variables as 'unknown' instead of 'any'. */
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// "alwaysStrict": true, /* Ensure 'use strict' is always emitted. */
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// "noUnusedLocals": true, /* Enable error reporting when a local variables aren't read. */
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// "noUnusedParameters": true, /* Raise an error when a function parameter isn't read */
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// "exactOptionalPropertyTypes": true, /* Interpret optional property types as written, rather than adding 'undefined'. */
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// "noImplicitReturns": true /* Enable error reporting for codepaths that do not explicitly return in a function. */,
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// "noFallthroughCasesInSwitch": true, /* Enable error reporting for fallthrough cases in switch statements. */
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// "noUncheckedIndexedAccess": true, /* Include 'undefined' in index signature results */
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// "noImplicitOverride": true, /* Ensure overriding members in derived classes are marked with an override modifier. */
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// "noPropertyAccessFromIndexSignature": true, /* Enforces using indexed accessors for keys declared using an indexed type */
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// "allowUnusedLabels": true, /* Disable error reporting for unused labels. */
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// "allowUnreachableCode": true, /* Disable error reporting for unreachable code. */
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/* Completeness */
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// "skipDefaultLibCheck": true, /* Skip type checking .d.ts files that are included with TypeScript. */
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"skipLibCheck": true /* Skip type checking all .d.ts files. */
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}
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}

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