Question_1854.md

LeetCode Records - Question 1854 Maximum Population Year

Attempt 1: Use an int[] and a nested loop to record the population

class Solution {
    public int maximumPopulation(int[][] logs) {
        int[] counts = new int[2051];

        for (int[] log : logs) {
            for (int i = log[0]; i < log[1]; i++) {
                counts[i]++;
            }
        }

        int max = counts[1950];
        int maxYear = 1950;
        for (int i = 1951; i <= 2050; i++) {
            if (counts[i] > max) {
                max = counts[i];
                maxYear = i;
            }
        }

        return maxYear;
    }
}

• Runtime: 1 ms (Beats: 44.68%)
• Memory: 42.10 MB (Beats: 11.02%)

Attempt 2: Use an int[] and a loop to record the change of population

class Solution {
    public int maximumPopulation(int[][] logs) {
        int[] counts = new int[2051];

        for (int[] log : logs) {
            counts[log[0]]++;
            counts[log[1]]--;
        }

        int sum = counts[1950];
        int max = counts[1950];
        int maxYear = 1950;
        for (int i = 1951; i <= 2050; i++) {
            sum += counts[i];
            if (sum > max) {
                max = sum;
                maxYear = i;
            }
        }

        return maxYear;
    }
}

• Runtime: 0 ms (Beats: 100.00%)
• Memory: 41.97 MB (Beats: 20.85%)