#include <vector> #include <climits> #include <iostream> using namespace std; class tree_array { public:     vector<int> vec;     int N;     tree_array(int n) {         int len = 0;         while (n >>= 1) len++;         N = 1<<(len+1);         vec = vector<int>(N, 0);     }     inline int lowbit(int t){ return t&(-t);}     int find(int i) {         int res = 0;         while (i > 0) {             res += vec[i-1];             i -= lowbit(i);         }         return res;     }     void insert(int n) {         for (int i = n; i <= N; i += lowbit(i))             vec[i-1] ++;     }     void pop(int n) {         for (int i = n; i <= N; i += lowbit(i))             vec[i-1] --;     }     void pop_front() {         int i = N;         while (vec[i-1] > 0) {             int temp = lowbit(i) >> 1;             vec[i-1]--; i -= temp;             if (!vec[i-1]) i -= temp;         }     } }; 第三题