UVA 1347 Tour

John Doe, a skilled pilot, enjoys traveling. While on vacation, he rents a small plane and starts visiting beautiful places. To save money, John must determine the shortest closed tour that connects his destinations. Each destination is represented by a point in the plane pi = < xi, yi > . John uses the following strategy: he starts from the leftmost point, then he goes strictly left to right to the rightmost point, and then he goes strictly right back to the starting point. It is known that the points have distinct x -coordinates. Write a program that, given a set of n points in the plane, computes the shortest closed tour that connects the points according to John’s strategy.

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【题目分析】
转化之后进行动态规划。详情请查看 这里（点我，^_^，点我）

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【代码】

#include<cstdio>#include<cstring>#include<cmath>double min(double x,double y){return x<y?x:y;}double map[1001][1001],dp[1001][1001],x[1001],y[1001];int main(){    int n;    while (scanf("%d",&n)==1)    {        for (int i=1;i<=n;i++)          scanf("%lf%lf",&x[i],&y[i]);        for (int i=1;i<=n;i++)          for (int j=1;j<=n;j++)            map[i][j]=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));        for (int i=1;i<n;i++)          dp[n][i]=map[i][n];        for (int i=n-1;i>=2;i--)          for (int j=i;j>=1;j--)            dp[i][j]=min(dp[i+1][j]+map[i][i+1],dp[i+1][i]+map[j][i+1]);        printf("%.2lf\n",dp[2][1]+map[1][2]);    }}