[POJ3067]Japan

题目链接：http://poj.org/problem?id=3067

 线段树和树状数组都可以做。

线段树：

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <queue>
#include <map>
#include <stack>
#include <list>
#include <vector>

using namespace std;

const int maxn = 3000010;

typedef long long LL;
typedef struct Node {
    int x;
    int y;
};

Node node[maxn];
int sum[maxn];
int num[maxn];

inline bool cmp(Node a, Node b) {
    if(a.y != b.y) {
        return a.y > b.y;
    }
    return a.x < b.x;
}

void update(int left, int right, int rt, int x) {
    if(left == right) {
        sum[rt]++;
        num[left]++;
        return ;
    }
    int mid = (left + right) >> 1;
    if(x <= mid) {
        update(left, mid, rt<<1, x);
    }
    else {
        update(mid+1, right, rt<<1|1, x);
    }
    sum[rt] = sum[rt<<1] + sum[rt<<1|1];
}

int query(int left, int right, int L, int R, int rt) {
    if(L <= left && R >= right) {
        return sum[rt];
    }
    int mid = (left + right) >> 1;
    int ans = 0;
    if(L <= mid) {
        ans += query(left, mid, L, R, rt<<1);
    }
    if(R > mid) {
        ans += query(mid+1, right, L, R, rt<<1|1);
    }
    return ans;
}

int n, m, k;
int res;
LL omega;

int main() {
    // freopen("in", "r", stdin);
    int kase = 1;
    int T;
    scanf("%d", &T);
    while(T--) {
        memset(sum, 0, sizeof(sum));
        memset(num, 0, sizeof(num));
        res = 0;
        omega = 0;
        scanf("%d %d %d", &n, &m, &k);
        for(int i = 1; i <= k; i++) {
            scanf("%d %d", &node[i].x, &node[i].y); 
        }
        sort(node+1, node+k+1, cmp);
        for(int i = 1; i <= k; i++) {
            int tmp = node[i].y;
            if(i > 1 && node[i].y == node[i-1].y) {
                res++;
            }
            else {
                res = 0;
            }
            omega += query(1, n, 1, node[i].x, 1) - num[node[i].x] - res;
            update(1, n, 1, node[i].x);
        }
        printf("Test case %d: %I64d
", kase++, omega);
    }
}

树状数组：

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <iostream>
#include <cmath>
#include <queue>
#include <map>
#include <stack>
#include <list>
#include <vector>

using namespace std;

const int maxn = 1000010;
typedef long long LL;
typedef struct Node {
    LL x;
    LL y;
};

Node node[maxn];
LL d[maxn<<1];
LL n, m, k;
LL ans;

inline bool cmp(Node a, Node b) {
    if(a.x != b.x) {
        return a.x > b.x;
    }
    return a.y > b.y;
}

//求某点管辖范围
LL lowbit(LL x) { //求x末尾最低位1的位置(末尾0的个数+1)
    // return x & (x ^ (x - 1));
    return x & (-x);
}

//区间更新树状数组(i到x)
void update(LL i, LL x, LL num) {
    while(i <= x) {    
        d[i] += num;
        i += lowbit(i);
    }
}

//获取前x项和
LL getsum(LL x) {
    LL sum = 0;
    while(x > 0) {
        sum += d[x];
        x -= lowbit(x);
    }
    return sum;
}

int main() {
    // freopen("in", "r", stdin); 
    LL kase = 1;
    LL T;
    scanf("%I64d", &T);
    while(T--) {
        memset(d, 0, sizeof(d));
        scanf("%I64d %I64d %I64d", &n, &m, &k);
        for(LL i = 1; i <= k; i++) {
            scanf("%I64d %I64d", &node[i].x, &node[i].y);
        }
        sort(node+1, node+k+1, cmp);
        ans = 0;
        for(int i = 1; i <= k; i++) {
            ans += getsum(node[i].y-1);
            update(node[i].y, m, 1);
        }
        printf("Test case %I64d: %I64d
", kase++, ans);
    }
}