【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。
1 /* 4325 */ 2 #include <iostream> 3 #include <cstdio> 4 #include <cstring> 5 #include <cstdlib> 6 #include <algorithm> 7 using namespace std; 8 9 #define MAXN 100005 10 11 typedef struct { 12 int s, t; 13 } node_t; 14 15 node_t nodes[MAXN]; 16 int qi[MAXN]; 17 int buf[MAXN*4]; 18 int sum[MAXN]; 19 20 inline int lowbit(int x) { 21 return -x&x; 22 } 23 24 void update(int i, int v, int n) { 25 while (i <= n) { 26 sum[i] += v; 27 i += lowbit(i); 28 } 29 } 30 31 int query(int i) { 32 int ret = 0; 33 34 while (i) { 35 ret += sum[i]; 36 i -= lowbit(i); 37 } 38 39 return ret; 40 } 41 42 int main() { 43 int t, n, m, l; 44 int i, j, k, tmp; 45 int a, b, c; 46 47 #ifndef ONLINE_JUDGE 48 freopen("data.in", "r", stdin); 49 #endif 50 51 scanf("%d", &t); 52 for (int tt=1; tt<=t; ++tt) { 53 scanf("%d %d", &n, &m); 54 l = 0; 55 for (i=0; i<n; ++i) { 56 scanf("%d %d", &nodes[i].s, &nodes[i].t); 57 buf[l++] = nodes[i].s; 58 buf[l++] = nodes[i].t; 59 } 60 for (i=0; i<m; ++i) { 61 scanf("%d", &qi[i]); 62 buf[l++] = qi[i]; 63 } 64 65 // discretization 66 buf[l++] = 0; 67 sort(buf, buf+l); 68 c = unique(buf, buf+l) - buf; 69 70 memset(sum, 0, sizeof(sum)); 71 for (i=0; i<n; ++i) { 72 a = lower_bound(buf, buf+c, nodes[i].s) - buf + 1; 73 b = lower_bound(buf, buf+c, nodes[i].t) - buf + 1; 74 update(a, 1, c); 75 update(b+1, -1, c); 76 } 77 78 printf("Case #%d:\n", tt); 79 for (i=0; i<m; ++i) { 80 j = lower_bound(buf, buf+c, qi[i]) - buf + 1; 81 k = query(j); 82 printf("%d\n", k); 83 } 84 } 85 86 return 0; 87 }
