UVALive4256[Salesmen] 动态规划

题目链接

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题目大意：给出一张图，然后给出一个序列，修改序列中一些数字，要求使这个序列相邻的两个点．要么是相同的点，要么在图中是相邻点；

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解题报告：

：dp[i][j]表示序列前i个数以j结尾需要修改的最小个数

dp[i][j]=min( dp[i-1][k] + (j==a[i])?0:1 ) k和j连通或相同

#include <cstdio>#include <vector>#include <cstring>#include <algorithm>using namespace std;const int maxn = 110;#define Inf 0x3f3f3f3fvector<int> G[maxn];int A[maxn*2], dp[maxn*2][maxn];int main(){    int T;    scanf("%d", &T );    while( T-- ) {        int n, m, l;        scanf("%d%d", &n, &m );        for ( int i=1; i<=n; i++ ) G[i].clear();        for ( int i=1; i<=n; i++ ) G[i].push_back(i);        for ( int i=1; i<=m; i++ ){            int x, y;            scanf("%d%d", &x, &y );            G[y].push_back(x);            G[x].push_back(y);        }        scanf("%d", &l );        for ( int i=1; i<=l; i++ ) scanf("%d", &A[i] );        for ( int i=1; i<=l; i++ )            for ( int j=1; j<=n; j++ ){                dp[i][j]=Inf;                for ( int k=0; k<G[j].size(); k++ ){                    if( j==A[i] )                        dp[i][j]=min(dp[i][j], dp[i-1][G[j][k]] );                    else                         dp[i][j]=min(dp[i][j], dp[i-1][G[j][k]]+1 );                }            }        int ans=Inf;        for ( int i=1; i<=n; i++ ) ans=min(ans, dp[l][i]);        printf("%d\n", ans);    }    return 0;}