MCO

Author: dolphingarlic

MCO/MCO 17-teleporter.cpp

@@ -0,0 +1,59 @@
+/*
+MCO 2017 Teleporters
+- Connected component DP
+- See comments in code
+- Complexity: O(N^2)
+*/
+
+#include <bits/stdc++.h>
+#define FOR(i, x, y) for (int i = x; i < y; i++)
+typedef long long ll;
+using namespace std;
+
+const ll MOD = 1e9 + 7;
+
+ll dp[2001][2001];
+
+int main() {
+    ios_base::sync_with_stdio(0);
+    cin.tie(0);
+    string S;
+    int s, e, n;
+    cin >> S >> s >> e;
+    n = S.size();
+
+    int st = 0, en = 0;
+    dp[0][0] = 1;
+    FOR(i, 1, n + 1) {
+        FOR(j, 1, i + 1) {
+            if (i == s) {
+                // We move from i to something greater than i
+                // That "greater than i" isn't present yet
+                if (S[i - 1] != 'L') dp[i][j] += dp[i - 1][j - 1];
+                // We move from i to something less than i.
+                // That "less than i" must already be present
+                if (S[i - 1] != 'R') dp[i][j] += dp[i - 1][j];
+            } else if (i == e) {
+                // We either append i to the end of a component or create an end
+                // component. We can do it no matter what S[i - 1] is since we
+                // don't go anywhere after this
+                dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1];
+            } else {
+                // We move to something greater than i. We either create a new
+                // component or append to an existing one from the back
+                if (S[i - 1] != 'L')
+                    dp[i][j] += max(0, j - st - en) * dp[i - 1][j - 1] +
+                                (j - en) * dp[i - 1][j];
+                // We move to something less than i. We either join 2 components
+                // or append to an existing one from the front 
+                if (S[i - 1] != 'R')
+                    dp[i][j] += j * dp[i - 1][j + 1] + (j - st) * dp[i - 1][j];
+            }
+            dp[i][j] %= MOD;
+        }
+        if (i == s) st++;
+        if (i == e) en++;
+    }
+    cout << dp[n][1];
+    return 0;
+}

README.md

@@ -52,6 +52,10 @@ This is a collection of the various olympiad problems I have solved
 
 [The Lithuanian Informatics Olympiad](http://www.lmio.mii.vu.lt/)
 
+### MCO
+
+The Malaysian Coding Olympiad
+
 ### NOI.cn
 
 [The National Olympiad in Informatics (China)](http://www.noi.cn/)

SACO/SACO 17-polynacci.py

@@ -0,0 +1,7 @@
+nums = list(map(int, input().split()))
+n = int(input())
+
+sm = sum(nums)
+for i in range(n - len(nums)):
+    nums[i % len(nums)], sm = sm, 2 * sm - nums[i % len(nums)]
+print(nums[(n - 1) % len(nums)])

SACO/SACO 19-triangle.cpp

@@ -0,0 +1,16 @@
+#include <bits/stdc++.h>
+#define FOR(i, x, y) for (int i = x; i < y; i++)
+typedef long long ll;
+using namespace std;
+
+int main() {
+    ios_base::sync_with_stdio(0);
+    cin.tie(0);
+    int a, b, c;
+    cin >> a >> b >> c;
+    if (a + b + c != 180) return cout << "IMPOSSIBLE", 0;
+    if (a == b && b == c) return cout << "EQUILATERAL", 0;
+    if (a != b && b != c && c != a) return cout << "SCALENE", 0;
+    cout << "ISOSCELES";
+    return 0;
+}