POJ2352 Stars
二维偏序。
按y排序，在x方向上用树状数组维护前缀和。
因为输入保证排好序了，所以y没什么用。
x可以等于０，所以最好在输入的时候加１，否则会TLE……
1 #include<cstdio> 2 #include<iostream> 3 #include<cmath> 4 #include<algorithm> 5 #include<cstring> 6 #include<cstdlib> 7 #include<cctype> 8 #include<vector> 9 #include<stack> 10 #include<queue> 11 using namespace std; 12 #define enter puts("") 13 #define space putchar(' ') 14 #define Mem(a, x) memset(a, x, sizeof(a)) 15 #define rg register 16 typedef long long ll; 17 typedef double db; 18 const int INF = 0x3f3f3f3f; 19 const db eps = 1e-8; 20 const int maxn = 3.2e4 + 5; 21 inline ll read() 22 { 23 ll ans = 0; 24 char ch = getchar(), last = ' '; 25 while(!isdigit(ch)) {last = ch; ch = getchar();} 26 while(isdigit(ch)) {ans = ans * 10 + ch - '0'; ch = getchar();} 27 if(last == '-') ans = -ans; 28 return ans; 29 } 30 inline void write(ll x) 31 { 32 if(x < 0) x = -x, putchar('-'); 33 if(x >= 10) write(x / 10); 34 putchar(x % 10 + '0'); 35 } 36 37 int n, ans[maxn]; 38 39 int c[maxn]; 40 int lowbit(int x) 41 { 42 return x & -x; 43 } 44 void add(int pos) 45 { 46 for(; pos < maxn; c[pos]++, pos += lowbit(pos)); 47 } 48 int query(int pos) 49 { 50 int ret = 0; 51 for(; pos; ret += c[pos], pos -= lowbit(pos)); 52 return ret; 53 } 54 55 int main() 56 { 57 n = read(); 58 for(int i = 1; i <= n; ++i) 59 { 60 int x = read() + 1, y = read(); 61 ans[query(x)]++; 62 add(x); 63 } 64 for(int i = 0; i < n; ++i) write(ans[i]), enter; 65 return 0; 66 }
