hdu6024 Building Shops(区间dp)

https://cn.vjudge.net/problem/HDU-6024

分开考虑某一点种与不种，最后取二者的最小值。

dp[i][1] = min(dp[i-1][0], dp[i-1][1])+c[i];

dp[i][0]则是j从i-1~1递减，判断当j种是，i的最小值，然后取总的最小。

注意dp初始化为INF，以及要开long long 

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cstdlib>
#include<cmath> 
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1
#define IO ios::sync_with_stdio(false);cin.tie(0);
#define INF 1e9
typedef long long ll;
using namespace std;
int n, m;
ll dp[100010][2];
typedef struct {
    ll x, c;
}Node;
Node node[100010];
bool cmp(const Node a, const Node b)
{
    return a.x<b.x;
}
int main()
{
    while(cin >> n){
        for(int i = 1; i <= n; i++){
            cin >> node[i].x >> node[i].c;
        }
        for(int i = 1; i <= n; i++){
            dp[i][0] = INF;
            dp[i][1] = INF;
        }
        dp[0][0]=0;dp[0][1]=0;
        sort(node+1, node+n+1, cmp);
        for(int i = 1; i <= n; i++){
            dp[i][1] = min(dp[i-1][0], dp[i-1][1])+node[i].c;
            ll tmp = 0;
            for(int j = i-1; j >= 1; j--){
                tmp += (i-j)*(node[j+1].x - node[j].x);//次数*长度
                dp[i][0] = min(dp[i][0], dp[j][1]+tmp);
            }
        }
        cout << min(dp[n][1], dp[n][0]) << endl;
    }
    return 0;
}