README_EN.md

1854. Maximum Population Year

中文文档

Description

You are given a 2D integer array logs where each logs[i] = [birthi, deathi] indicates the birth and death years of the ith person.

The population of some year x is the number of people alive during that year. The ith person is counted in year x's population if x is in the inclusive range [birthi, deathi - 1]. Note that the person is not counted in the year that they die.

Return the earliest year with the maximum population.

 

Example 1:

Input: logs = [[1993,1999],[2000,2010]]
Output: 1993
Explanation: The maximum population is 1, and 1993 is the earliest year with this population.

Example 2:

Input: logs = [[1950,1961],[1960,1971],[1970,1981]]
Output: 1960
Explanation: 
The maximum population is 2, and it had happened in years 1960 and 1970.
The earlier year between them is 1960.

 

Constraints:

• 1 <= logs.length <= 100
• 1950 <= birthi < deathi <= 2050

Solutions

Python3

class Solution:
    def maximumPopulation(self, logs: List[List[int]]) -> int:
        offset = 1950
        delta = [0] * 101
        for birth, death in logs:
            delta[birth - offset] += 1
            delta[death - offset] -= 1
        mx = cur = res = 0
        for i in range(101):
            cur += delta[i]
            if mx < cur:
                mx = cur
                res = i
        return res + offset

Java

class Solution {
    public int maximumPopulation(int[][] logs) {
        int offset = 1950;
        int[] delta = new int[101];
        for (int[] log : logs) {
            ++delta[log[0] - offset];
            --delta[log[1] - offset];
        }
        int mx = 0, cur = 0, res = 0;
        for (int i = 0; i < 101; ++i) {
            cur += delta[i];
            if (mx < cur) {
                mx = cur;
                res = i;
            }
        }
        return res + offset;
    }
}

JavaScript

/**
 * @param {number[][]} logs
 * @return {number}
 */
var maximumPopulation = function(logs) {
    const offset = 1950;
    const len = 2050 - 1950 + 1;
    let delta = new Array(len).fill(0);
    for (let log of logs) {
        delta[log[0] - offset] += 1;
        delta[log[1] - offset] -= 1;
    }
    let max = 0;
    let total = 0;
    let index = 0;
    for (let i = 0; i < len; i++) {
        total += delta[i];
        if (total > max) {
            max = total;
            index = i;
        }
    }
    return index + offset;
};

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