複習線段樹

查找任意區間最小值的下標

#include <bits/stdc++.h>

using namespace std;
#define lson L, mid, rt << 1
#define rson mid + 1, R, rt << 1 | 1
#define N 1000 + 10

int n, Min[N << 2], a[N];

void pushup(int rt){
    if(a[Min[rt << 1]] <= a[Min[rt << 1 | 1]])
        Min[rt] = Min[rt << 1];
    else Min[rt] = Min[rt << 1 | 1];
}

void build(int L, int R, int rt){
    if(L == R){
        Min[rt] = L;
        return ;
    }
    int mid = (L +  R) >> 1;
    build(lson); build(rson);
    pushup(rt);
}

int query(int l, int r, int L, int R, int rt){
    if(l <= L && R <= r){
        return Min[rt];
    }
    int mid = (L + R) >> 1;
    if(r <= mid) return query(l, r, lson);
    else if(l > mid) return query(l, r, rson);
    else {
        int tl = query(l, mid, lson), tr = query(mid + 1, r, rson);
        if(a[tl] <= a[tr]) return tl;
        else return tr;
    }
}

int main(){
    while(~scanf("%d", &n)){
        for(int i = 1; i <= n; i++) scanf("%d", a + i);
        build(1, n, 1);
        int q;
        scanf("%d", &q);
        while(q--){
            int l, r;
            scanf("%d%d", &l, &r);
            printf("ANS IS : %d\n", query(l, r, 1, n, 1));
        }
    }
    return 0;
}

/*

7
3 4 8 5 4 3 2
10

*/