TCO 2013 1C

1、晚上一点多爬起来太痛苦了，脑子晕乎乎的，第一个都没做出来~~~~

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <stack>
#include <algorithm>
#include <list>
#include <ctime>
#include <set>
#include <queue>
typedef long long ll;
using namespace std;

class TheArray {
public:
    int find(int n, int d, int first, int last) {
        if (first > last)
            swap(first, last);
        if(0==d)
            return first;
        int res;
        int cost=(last-first)/d;
        int start=first+cost*d;
        int r=(n-1-cost);
        if(last==start){
            if((r%2)==0){
                res=start+d*(r/2);
            }else
                res=start+d*((r-1)/2);
        }else{
            if((r%2)==0){
                res=start+d*(r/2);
            }else
                res=last+d*((r-1)/2);
        }
        return res;
    }
};

 2、二分法的应用

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <stack>
#include <algorithm>
#include <list>
#include <ctime>
#include <set>
#include <queue>
typedef long long ll;
using namespace std;

class TheOlympiadInInformatics {
public:
    int find(vector<int> sums, int k) {
        int sz = sums.size();
        ll start = 1;
        ll end = 1000000001;
        int res = 0;
        if (k == 0) {
            for (int i = 0; i < sz; i++) {
                res = max(res, sums[i]);
            }
            return res;
        }

        while (start < end) {
            ll mid = (start + end) / 2;
            ll num = 0;
            for (int i = 0; i < sz; i++) {
                num += (sums[i] / mid);
            }
            if (num > k) { //不行
                start = mid + 1;
            } else { //行
                end = mid;
            }
        }
        res = end-1;
        return res;
    }
};