50 lines
1.2 KiB
C++
50 lines
1.2 KiB
C++
#include <iostream>
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#include <cmath>
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#include <algorithm>
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#include <string.h>
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using namespace std;
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const int MAXN = 501;
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struct data { double x,y;
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}p[MAXN];
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inline double sqr(double x)
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{
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return x * x;
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}
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double dis(int a,int b)
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{
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return sqrt(sqr(p[a].x - p[b].x) + sqr(p[a].y - p[b].y));
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}
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bool cmp(data a,data b)
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{
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return a.x == b.x ? a.y < b.y : a.x < b.x;
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}
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int main()
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{
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int n;
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double dp[MAXN][MAXN];
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while (scanf("%d",&n) != EOF && n)
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{
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for (int i = 1;i <= n;i++)
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scanf("%lf%lf",&p[i].x,&p[i].y);
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sort(p,p+n+1,cmp);
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memset(dp,0,sizeof(dp));
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for (int i = 0;i <= n;i++)
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for (int j = 0;j <= n;j++)
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dp[i][j] = 1e20;
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dp[0][0] = 0;
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for (int i = 0;i < n;i++)
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for (int j = 0;j <= i;j++)
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{
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dp[i+1][j] = min(dp[i+1][j],dp[i][j] + dis(i,i+1));
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dp[i+1][i] = min(dp[i+1][i],dp[i][j] + dis(j,i+1));
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}
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double ans = 1e20;
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for (int i = 0;i <= n;i++)
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{
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if (dp[n][i] + dis(i,n) < ans)
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ans = dp[n][i] + dis(i,n);
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}
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printf("%.2lf\n",ans);
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}
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}
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