题目连接:http://acm.uestc.edu.cn/#/problem/show/931
OJ评判系统有些坑,不支持__int64以及输出的%I64d大家注意。全开long long也会TLE,比较坑。逆序的基础操作题,不错。
1 #include <bits/stdc++.h> 2 #define MAX 100010 3 using namespace std; 4 5 int s[MAX * 10]; 6 7 struct Node { 8 int x, v; 9 } node[MAX]; 10 11 bool cmp (Node a, Node b) { 12 if (a.x == b.x) { 13 return a.v > b.v; 14 } 15 return a.x < b.x; 16 } 17 18 int lowbit (int x) { 19 return x & (-x); 20 } 21 22 int sum (int p) { 23 int ans = 0; 24 while (p) { 25 ans += s[p]; 26 p -= lowbit(p); 27 } 28 return ans; 29 } 30 31 void add (int p, int del) { 32 while (p <= 1000000) { 33 s[p] += del; 34 p += lowbit(p); 35 } 36 } 37 38 int main () { 39 int n, i; 40 while (scanf("%d", &n) != EOF) { 41 long long ans = 0; 42 for (i = 0; i < n; ++ i) { 43 scanf("%d %d", &node[i].x, &node[i].v); 44 } 45 sort (node, node + n, cmp); 46 memset(s, 0, sizeof(s)); 47 for (i = 0; i < n; ++ i) { 48 ans = ans + i - sum(node[i].v); 49 add(node[i].v, 1); 50 } 51 printf ("%lld\n", ans); 52 } 53 return 0; 54 }
时间: 2024-10-07 05:16:10