2
2
1 10
3
2 5 4

Case #1:
0
Case #2:
1

这题窝觉得贪心才是才是正解，但是贪心没贪出来，QAQ，二分更好想

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <vector>
#include <queue>
using namespace std;

typedef long long LL;
const int MOD = 1e9 + 7;
const int INF = 0x7fffffff;
const int N = 1e6 + 10;

int a[N], n;

bool f(int x) {
    int pre = a[0] - x;
    for(int i = 1; i < n; i++) {
        if(pre  >= x + <span style="font-family: Arial, Helvetica, sans-serif;">a[i]</span>) return false;
        else pre = max(a[i] - x, pre + 1);//pre+1是看当前减去x是否小于pre-1，如果是则不能
    }
    return true;
}
int main() {
    int T, C = 1;
    scanf("%d", &T);
    while(T--) {
        scanf("%d", &n);
        for(int i = 0; i < n; i++) {
            scanf("%d", &a[i]);
        }
        int ans = 0;
        int l = 0, r = 1e7, mid;
        while(r >= l) {
            int mid = (l + r) / 2;
            if(f(mid)) {
                ans = mid;
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        printf("Case #%d:\n%d\n", C++, ans);
    }
    return 0;
}

百度之星初赛1002（二分搜索）

原文：http://blog.csdn.net/u013445530/article/details/46277839