Bzoj 3400(单调栈)

BZOJ 3400
Luogu 2947
from: USACO 2009 Mar Sliver(USACO刷题第19题)

维护一个从顶到底单调递减的单调栈然后就可以求解了。

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<queue>
#define ms(i, j) memset(i, j, sizeof i)
using namespace std;

const int MAXN = 100000 + 5;

int n, ans[MAXN], hi[MAXN], st[MAXN], top;

void clean() {
    top = 0;
    ms(st, 0);
}
void init() {
    clean();
    for (int i=1;i<=n;i++) scanf("%d", &hi[i]);
}
void solve() {
    for (int i=n;i>=1;i--) {
        while (top&&hi[i]>=hi[st[top]]) top--;
        ans[i] = st[top];
        st[++top] = i;
    }
    for (int i=1;i<=n;i++) printf("%d\n", ans[i]);
}
int main() {
    #ifndef ONLINE_JUDGE
    freopen("1.in", "r", stdin);freopen("1.out", "w", stdout);
    #endif
    while (scanf("%d", &n)==1) init(), solve();
    return 0;
}