algorithm/Week_03/id_142/LeetCode_997_142.java at master · feixiangcode/algorithm · GitHub

26 lines (25 loc) · 875 Bytes

class Solution {

public int findJudge(int N, int[][] trust) {

int[] trustArr = new int[N + 1]; // how many people this person trusts

int[] trustedArr = new int[N + 1]; // how many people trust this person

for (int[] pair : trust) {

trustArr[pair[0]]++;

trustedArr[pair[1]]++;

}

int judge = -1;

for (int i = 1; i <= N; i++) {

if (trustArr[i] == 0) { // not trust anyone, may be the judge

if (judge == -1) {

judge = i; // update judge

} else {

return -1; // got the second judge, return -1

}

// the judge must be trusted by N-1 people.

if (judge != -1 && trustedArr[judge] == N - 1) {

return judge;

}

return -1;

}

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