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package class_2021_12_5_week ;
import java.util.ArrayList ;
// 测试链接 : https://leetcode.com/problems/loud-and-rich/
public class Code01_LoudAndRich {
// richer[i] = {a, b} a比b更有钱 a -> b
// quiet[i] = k, i这个人安静值是k
public static int [ ] loudAndRich ( int [ ] [ ] richer , int [ ] quiet ) {
int N = quiet . length ;
// a -> b
// a -> c
// b -> c
// a : b c
// b : c
// nexts[0] = {5,7,3}
// 0 : 5 7 3
// 5最没钱的,
// nexts[5] = { }
ArrayList < ArrayList < Integer > > nexts = new ArrayList < > ( ) ;
for ( int i = 0 ; i < N ; i + + ) {
// 0 : {}
// 1 : {}
// n-1 : {}
nexts . add ( new ArrayList < > ( ) ) ;
}
// 入度
// 0 : 0
// 1 : 2
int [ ] degree = new int [ N ] ;
for ( int [ ] r : richer ) {
// [a,b] a -> b
nexts . get ( r [ 0 ] ) . add ( r [ 1 ] ) ;
degree [ r [ 1 ] ] + + ;
}
// 所有入度为0的点, 入队列
int [ ] zeroQueue = new int [ N ] ;
int l = 0 ;
int r = 0 ;
for ( int i = 0 ; i < N ; i + + ) {
if ( degree [ i ] = = 0 ) {
zeroQueue [ r + + ] = i ;
}
}
// ans[i] = j : 比i有钱的所有人里, j最安静
int [ ] ans = new int [ N ] ;
for ( int i = 0 ; i < N ; i + + ) {
ans [ i ] = i ;
}
while ( l < r ) { // 如果队列不空
// 弹出一个入度为0的点
int cur = zeroQueue [ l + + ] ;
// 1) 消除当前cur的影响!
for ( int next : nexts . get ( cur ) ) {
// cur : 比cur有钱, 最安静的! ans[cur]
if ( quiet [ ans [ next ] ] > quiet [ ans [ cur ] ] ) {
ans [ next ] = ans [ cur ] ;
}
if ( - - degree [ next ] = = 0 ) {
zeroQueue [ r + + ] = next ;
}
}
}
return ans ;
}
}