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:
        delta = [0] * 2055
        for birth, death in logs:
            delta[birth] += 1
            delta[death] -= 1

        mx = res = cur = 0
        for i, v in enumerate(delta):
            cur += v
            if mx < cur:
                mx = cur
                res = i
        return res

Java

class Solution {
    public int maximumPopulation(int[][] logs) {
        int[] delta = new int[2055];
        for (int[] log : logs) {
            ++delta[log[0]];
            --delta[log[1]];
        }
        int res = 0, mx = 0, cur = 0;
        for (int i = 0; i < delta.length; ++i) {
            cur += delta[i];
            if (cur > mx) {
                mx = cur;
                res = i;
            }
        }
        return res;
    }
}

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;
};

C++

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

Go

func maximumPopulation(logs [][]int) int {
	delta := make([]int, 101)
	offset := 1950
	for _, log := range logs {
		delta[log[0]-offset]++
		delta[log[1]-offset]--
	}
	res, mx, cur := 0, 0, 0
	for i := 0; i < len(delta); i++ {
		cur += delta[i]
		if cur > mx {
			mx = cur
			res = i
		}
	}
	return res + offset
}

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