第十五章動態規劃之“最長公用子序列”

時間複雜度為O(m*n)，就是兩個迴圈。

#include <iostream>using namespace std;void LCSLength(char *x,char *y,int m,int n,int (*c)[7],int (*b)[7]){for(int i=0;i<=m;i++){c[i][0]=0;}for(int i=0;i<=n;i++){c[0][i]=0;}for(int i=1;i<=m;i++){for(int j=1;j<=n;j++){if(x[i]==y[j]){c[i][j]=c[i-1][j-1]+1;b[i][j]=0;}else{if(c[i][j-1]>c[i-1][j]){c[i][j]=c[i][j-1];b[i][j]=1;}else{c[i][j]=c[i-1][j];b[i][j]=2;}}}}}void PrintLCS(int (*b)[7],char *x,int i,int j){if(i==0||j==0){return;}if(b[i][j]==0){PrintLCS(b,x,i-1,j-1);cout<<x[i]<<" ";}else if(b[i][j]==1){PrintLCS(b,x,i,j-1);}else{PrintLCS(b,x,i-1,j);}}int main(){int m=7;int n=6;char x[8]={' ','A','B','C','B','D','A','B'};char y[7]={' ','B','D','C','A','B','A'};int c[8][7],b[8][7];LCSLength(x,y,m,n,c,b);PrintLCS(b,x,m,n);//cout<<c[7][6]<<" "<<b[7][6];system("pause");}