Maximum Population Year
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
思路一：求交集问题，看了一下范围 [1950, 2050]，直接用数组模拟交集范围即可
public int maximumPopulation(int[][] logs) {
int[] years = new int[101];
for (int[] pYear : logs) {
for (int i = pYear[0]; i < pYear[1]; i++) {
years[i - 1950]++;
}
}
int max = 0;
int idx = 0;
for (int i = 0; i < years.length; i++) {
if (years[i] > max) {
max = years[i];
idx = i;
}
}
return 1950 + idx;
}