【HDOJ】4325 Flowers

树状数组+离散化的题目，一直在思考为什么结果不一样，后来才发现花开了就是开了不会再谢了。

/* 4325 */
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
using namespace std;

#define MAXN 100005

typedef struct {
    int s, t;
} node_t;

node_t nodes[MAXN];
int qi[MAXN];
int buf[MAXN*4];
int sum[MAXN];

inline int lowbit(int x) {
    return -x&x;
}

void update(int i, int v, int n) {
    while (i <= n) {
        sum[i] += v;
        i += lowbit(i);
    }
}

int query(int i) {
    int ret = 0;
    
    while (i) {
        ret += sum[i];
        i -= lowbit(i);
    }
    
    return ret;
}

int main() {
    int t, n, m, l;
    int i, j, k, tmp;
    int a, b, c;
    
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
    #endif
    
    scanf("%d", &t);
    for (int tt=1; tt<=t; ++tt) {
        scanf("%d %d", &n, &m);
        l = 0;
        for (i=0; i<n; ++i) {
            scanf("%d %d", &nodes[i].s, &nodes[i].t);
            buf[l++] = nodes[i].s;
            buf[l++] = nodes[i].t;
        }
        for (i=0; i<m; ++i) {
            scanf("%d", &qi[i]);
            buf[l++] = qi[i];
        }
        
        // discretization
        buf[l++] = 0;
        sort(buf, buf+l);
        c = unique(buf, buf+l) - buf;
        
        memset(sum, 0, sizeof(sum));
        for (i=0; i<n; ++i) {
            a = lower_bound(buf, buf+c, nodes[i].s) - buf + 1;
            b = lower_bound(buf, buf+c, nodes[i].t) - buf + 1;
            update(a, 1, c);
            update(b+1, -1, c);
        }
        
        printf("Case #%d:
", tt);
        for (i=0; i<m; ++i) {
            j = lower_bound(buf, buf+c, qi[i]) - buf + 1;
            k = query(j);
            printf("%d
", k);
        }
    }
    
    return 0;
}