POJ2352 Stars
原题链接:http://poj.org/problem?id=2352
线段树,单点更新,区间查询,200+ms。
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1 #include <stdio.h> 2 #include <string.h> 3 #define lson (cur << 1) 4 #define rson (cur << 1 | 1) 5 #define N 32005 6 7 int tree[N << 2], ans[15001]; 8 9 void pushup(int cur) 10 { 11 tree[cur] = tree[lson] + tree[rson]; 12 } 13 14 void insert(int cur, int l, int r, int x) 15 { 16 if(l == r) 17 { 18 tree[cur] ++; 19 return ; 20 } 21 int mid = (l + r) >> 1; 22 if(mid >= x) 23 insert(lson, l, mid, x); 24 else 25 insert(rson, mid + 1, r, x); 26 pushup(cur); 27 } 28 29 void query(int cur, int l, int r, int s, int t, int &lv) 30 { 31 if(l >= s && r <= t) 32 { 33 lv += tree[cur]; 34 return ; 35 } 36 int mid = (l + r) >> 1; 37 if(mid >= s) 38 query(lson, l, mid, s, t, lv); 39 if(mid + 1 <= t) 40 query(rson, mid + 1, r, s, t, lv); 41 } 42 43 int main() 44 { 45 int n, i, x, y, lv; 46 scanf("%d", &n); 47 for(i = 0; i < n; i ++) 48 { 49 scanf("%d%d", &x, &y); 50 lv = 0; 51 query(1, 1, N, 1, x + 1, lv); 52 ans[lv] ++; 53 insert(1, 1, N, x + 1); 54 } 55 for(i = 0; i < n; i ++) 56 { 57 printf("%d\n", ans[i]); 58 } 59 return 0; 60 }
树状数组,140+ms。
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1 #include <cstdio> 2 #include <cstring> 3 #define N 15005 4 #define M 32005 5 int a[N], c[M]; 6 7 int lowbit(int x) 8 { 9 return x & (-x); 10 } 11 12 void update(int v) 13 { 14 while(v < M) 15 { 16 c[v] ++; 17 v += lowbit(v); 18 } 19 } 20 21 int sum(int v) 22 { 23 int ans = 0; 24 while(v) 25 { 26 ans += c[v]; 27 v -= lowbit(v); 28 } 29 return ans; 30 } 31 32 int main() 33 { 34 int n, i, x, y; 35 scanf("%d", &n); 36 for(i = 0; i < n; i ++) 37 { 38 scanf("%d%d", &x, &y); 39 ++ x; 40 a[sum(x)] ++; 41 update(x); 42 } 43 for(i = 0; i < n; i ++) 44 printf("%d\n", a[i]); 45 return 0; 46 }