zoj1276矩阵连乘dp

很经典的入门dp

/*******************************************************************************/
/* OS           : 3.2.0-58-generic #88-Ubuntu SMP Tue Dec 3 UTC 2013 GNU/Linux
 * Compiler     : g++ (GCC)  4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)
 * Encoding     : UTF8
 * Date         : 2014-03-23
 * All Rights Reserved by yaolong.
*****************************************************************************/
/* Description: ***************************************************************
*****************************************************************************/
/* Analysis: ******************************************************************
*****************************************************************************/
/*****************************************************************************/

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
#define INF 1<<30
#define MAX 100
int m[MAX][MAX],s[MAX][MAX],p[MAX];
void MatrixChain(int n){
    int i,j,l,q,k;
    for(i=1;i<=n;i++)
       m[i][i]=0;   //自己乘自己
    for(l=2;l<=n;l++)
       for(i=1;i<=n-l+1;i++){
         j=i+l-1;
         m[i][j]=INF;

         for(k=i;k<=j-1;k++){
            q=m[i][k]+m[k+1][j]+p[i-1]*p[k]*p[j];
            if(q<m[i][j]){
                m[i][j]=q;
                s[i][j]=k;

            }
         }
       }

}
void trace_back(int i,int j){
    if(i==j) {cout<<"A"<<i; return;}
    cout<<"(";
    trace_back(i,s[i][j]);
    cout<<" x ";
    trace_back(s[i][j]+1,j);
    cout<<")";

}
int main(){
    #ifndef ONLINE_JUDGE
    freopen("in.txt","r",stdin);
    #endif
    int i,n,cases=1;
    while(cin>>n&&n){

     for(i=1;i<=n;i++){
        cin>>p[i-1]>>p[i];
     }
     cout<<"Case "<<cases++<<": ";
        MatrixChain(n);
        trace_back(1,n);
        cout<<endl;

    }

    #ifndef  ONLINE_JUDGE
    fclose(stdin);
    #endif

    return 0;

}

其实我觉得题目输入冗余太高了……完全没必要。。。。wa了一次，因为没有写case x: ..