Lost Cows POJ - 2182 二分 + 树状数组

Code:

#include<cstdio>
#include<stack>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn = 100000 + 233;
int n, C[maxn], height[maxn];
stack<int>S;
inline int lowbit(int t) { return t & (-t);}
inline void update(int x, int delta)
{
    while(x <= n) C[x] += delta, x += lowbit(x);
}
inline int query(int x)
{
    int sum = 0;
    while(x > 0) sum += C[x], x -=lowbit(x);
    return sum;
}
int main()
{
    scanf("%d",&n);
    height[1] = 0;
    for(int i = 2;i <= n; ++i) scanf("%d",&height[i]);
    for(int i = 1;i <= n; ++i) update(i, 1);
    for(int i = n;i >= 1; --i)
    {
        int l = 1, r = n, ans = 0;
        while(l <= r)
        {
            int mid = (l + r) >> 1;
            if(query(mid) >= height[i] + 1) ans = mid, r = mid - 1;
            else l = mid + 1;
        }
        update(ans, -1);
        S.push(ans);
    }
    while(!S.empty()) {printf("%d\n",S.top()); S.pop();}
    return 0;
}