UVA - 116 Unidirectional TSP 多段图的最短路

来源：互联网发布：自动点击网页软件编辑：程序博客网时间：2024/05/03 19:00

题目大意：给出一个矩阵，要求每列都要路过，起点必须是第一列，求经过的最短路径的上面的数字和最小

解题思路：公式为d[i][j] = min(d[i][j+1],d[i+1][j+1],d[i-1][j+1]) + a[i][j]，本题要注意，因为可以从最上面一行到最后一行，或者从最后一行到第一行，注意i的变化

#include<cstdio>#include<algorithm>#include<cstring>using namespace std;const int maxn = 300 + 10;int row,col;int DP[maxn][maxn];int m[maxn][maxn];int ans[maxn][maxn];int main() {while(scanf("%d%d",&row,&col) != EOF) {for(int i = 1; i <= row; i++)for(int j = 1; j <= col; j++) scanf("%d", &m[i][j]);memset(ans,0,sizeof(ans));int min_ = 0x3f3f3f3f;int first;for(int i = col; i >= 1; i--)  {for(int j = 1; j <= row; j++) {if(i == col)DP[j][i] = m[j][i];else{int mov[3] = {j,j-1,j+1};if(j == row)mov[2] = 1;if(j == 1)mov[1] = row;sort(mov,mov+3);DP[j][i] = 0x3f3f3f3f;for(int k = 0; k < 3; k++) {int temp = DP[mov[k]][i+1] + m[j][i];if(temp < DP[j][i]) {DP[j][i] = temp;ans[j][i] = mov[k];}}}if(i == 1 && DP[j][i] < min_) {min_ = DP[j][i];first = j;}}}printf("%d",first);int i,j;for(i = ans[first][1],j = 2; j <= col;i = ans[i][j],j++)printf(" %d",i);printf("\n");printf("%d\n",min_);}return 0;}

0 0