LD编辑距离算法-->可用于聊天系统的刷屏控制

/*1  Set n to be the length of s.Set m to be the length of t.If n = 0, return m and exit.If m = 0, return n and exit.Construct a matrix containing 0..m rows and 0..n columns.2 Initialize the first row to 0..n.Initialize the first column to 0..m.3 Examine each character of s (i from 1 to n).4 Examine each character of t (j from 1 to m).5 If s[i] equals t[j], the cost is 0.If s[i] doesn't equal t[j], the cost is 1.6 Set cell d[i,j] of the matrix equal to the minimum of:a. The cell immediately above plus 1: d[i-1,j] + 1.b. The cell immediately to the left plus 1: d[i,j-1] + 1.c. The cell diagonally above and to the left plus the cost: d[i-1,j-1] + cost.7 After the iteration steps (3, 4, 5, 6) are complete, the distance is found in cell d[n,m].*/#include <iostream>#include <vector>#include <string>using namespace std;int ldistance(const string source,const string target){    int n=source.length();    int m=target.length();    if (m==0) return n;    if (n==0) return m;        typedef vector< vector<int> >  Tmatrix;    Tmatrix matrix(n+1);    for(int i=0; i<=n; i++)  matrix[i].resize(m+1);    for(int i=1;i<=n;i++) matrix[i][0]=i;    for(int i=1;i<=m;i++) matrix[0][i]=i;     for(int i=1;i<=n;i++)     {        const char si=source[i-1];        for(int j=1;j<=m;j++)        {            const char dj=target[j-1];            int cost;            if(si==dj){                cost=0;            }            else{                cost=1;            }            const int above=matrix[i-1][j]+1;            const int left=matrix[i][j-1]+1;            const int diag=matrix[i-1][j-1]+cost;            matrix[i][j]=min(above,min(left,diag));        }     }      return matrix[n][m];}int main(){    string s;    string d;    cout<<"source=";    cin>>s;    cout<<"diag=";    cin>>d;    int dist=ldistance(s,d);    cout<<"dist="<<dist<<endl;}

本人用该程序在聊天服务器内部识别刷屏用户，效果不错