POJ 2128 Highways

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Highways

原题:Highways
题意:高速公路上有n个站,n-1条单向路径,新来的市长希望加两条路满足任意两个城市都能相互到达,并使得距离最短
解法:看样例数据都看得出来,头尾延伸一条反向路,并使得两条路径重复覆盖的距离最小,即找一条最短的路

#include<iostream>using namespace std;int main(){    int n;    cin >> n;    int f[50000], sum=0, min, k=1;    for(int i = 0; i < n-1; i++){        cin >> f[i];    }    for(int i = n-2; i > 0; i--){        f[i]=f[i]-f[i-1];    }    for(int i = 0; i < n-1; i++) sum += f[i];    min = 2*1e9;    for(int i = 1; i < n-2; i++){        if (f[i] < min){            min=f[i];            k=i;        }    }    sum += min;    if(n < 4){        cout << "0" << endl;    } else {        cout << sum << endl;        cout << k+2 << " " << "1" << " " << n << " " << k+1 << endl;    }}
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