1854. Maximum Population Year

Problem Statement

Pattern:

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Solution

public int maximumPopulation (int[][] logs){
	final int MIN_YEAR = 1950, MAX_YEAR = 2050;
	int[] population = new int[MAX_YEAR-MIN_YEAR+1];
 
	// for each log
	for(int[] log : logs){
		// increment birth year population
		population[log[0]-1950]++;
		// decrement death year population
		population[log[1]-1950]--;
	}
	
	// convert to prefix sum to get true population
	for (int i = 1; i < population.length; i++)
		population[i] += population[i-1];
	
	// find maxYear
	int maxYear = 0;
	for (int i = 0; i < population.length; i++)
		if(population[i] > population[maxYear]) maxYear = i;
	
	// offset to get answer
	return maxYear+1950;
}

Notes