hdu 3484 Interviewe RMQ+二分

 #include <cstdio>
 #include <iostream>
 #include <algorithm>
 using namespace std;
 const int maxn =  + ;
 int a[maxn];
 int maxsum[maxn][];
 int n, k;

 void RMQ(int num){
     for (int i = ; i <= num; i++){
         maxsum[i][] = a[i];
     }

     for (int j = ; j < ; j++){
         for (int i = ; i <= num; i++){
             if (i + ( << j) -  <= num){
                 maxsum[i][j] = max(maxsum[i][j - ], maxsum[i + ( << (j - ))][j - ]);
             }
         }
     }
     return;
 }

 //获取[x,y]的最大值
 int getmax(int x, int y){
     int k1 = (int)(log((double)(y - x + )) / log(2.0));
     return max(maxsum[x][k1], maxsum[y - ( << k1) + ][k1]);
 }

 //获取m人的最大值(m组)
 int Find(int m){
     int ans = ;
     int num = n / m;//每组num个人
     for (int i = ; i < m; i++){
         ans += getmax( + i*num, (i + )*num);
         if (ans > k)
             return ans;
     }
     return ans;
 }

 int main(){
     while (~scanf("%d%d", &n, &k)){
         if (n == - && k == -)
             break;
         int sum = ;
         bool ok_1 = false;
         for (int i = ; i <= n; i++){
             scanf("%d", &a[i]);
             if (a[i] > k){
                 ok_1 = true;
             }
             sum += a[i];
         }
         if (ok_1){
             printf("1\n");
             continue;
         }
         if (sum < k){
             printf("-1\n");
             continue;
         }
         if (sum == k){
             printf("%d\n", k);
             continue;
         }
         //初始化
         RMQ(n);
         bool ok = false;
         int l = ;
         int r = n;
         int ans = ;
         int mid, t;
         while (l <= r){
             mid = (l + r) / ;
             t = Find(mid);
             if (t > k){
                 r = mid - ;
                 ans = mid;
                 ok = true;
             }
             else{
                 l = mid + ;
             }
         }
         if (ok)
             printf("%d\n", ans);
         else
             printf("-1\n");
     }
     //system("pause");
     return ;
 }