二分搜索模板

 1 int bs1(int x,int y,int t) {  //二分求上界 
 2     while(x <= y) {
 3         int mid = x + (y - x) / 2;
 4         if(num[mid] <= t) x = mid + 1;
 5         else y = mid - 1;
 6     }
 7     return x;
 8 }
 9 int bs2(int x,int y,int t) { //二分求下界 
10     while(x <= y) {
11         int mid = x + (y - x) / 2;
12         if(num[mid] >= t) x = mid + 1;
13         else y = mid - 1;
14     }
15     return x;
16 }