【P2947】 [USACO09MAR]Look Up S单调栈

链接

code

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cctype>
#include <vector>
#include <iostream>
#include <map>

using namespace std;
inline int read(){
    int x = 0, op = 1; char ch = getchar();
    while (!isdigit(ch)){
        if (ch == '-') op = -1; ch = getchar();}
    while (isdigit(ch)){
        x = (x << 1) + (x << 3) + (ch ^ 48);
        ch = getchar();
    }
    return x * op;
}
inline void write(int x){
    if (x < 0) putchar('-'), x = - x;
    if (x > 9) write(x / 10);
    putchar('0' + x % 10);
}

const int N = 1e5 + 100;
int a[N], st[N], res[N];

int main() {
#ifdef DEBUG
    freopen("in.txt", "r", stdin);
#endif
    int n = read();
    for (int i = 1; i <= n; ++i) {
        a[i] = read();
    }
    int s = 0;
    for (int i = 1; i <= n; ++i) {
        st[++s] = i;
        while (s && a[st[s - 1]] < a[st[s]]){
            res[st[s - 1]] = st[s];
            st[s - 1] = st[s];
            s--;
        }
    }
    for (int i = 1; i <= n; ++i) {
        write(res[i]), putchar('\n');
    }
}