华为OJ（最大公共子串长度）

c++实现

#include 
#include 

using namespace std;
/*
s1 = "abc"
s2 = "cabcd"
dp[i][j]
--------------------------------
  ----  0    1    2    3    4
  ------------------------------
  0 --  0    1    0    0    0 
  ------------------------------
  1 --  0    0    2    0    0
  ------------------------------
  2 --  1    0    0    3    0
--------------------------------
*/
int main() {
  string s1,s2;
  while(cin>>s1>>s2) {
    if(s1.length()>s2.length()) { //短的为s1，长的为s2
      string t = s1;
      s1 = s2;
      s2 = t;
    }
    int dp[s1.length()][s2.length()];
    for(int i=0;i<s2.length();i++) { //dp[i][j]第一行，s1[0]和s2[i]相等就把dp[0][i]设为1，否则为0
      if(s1[0] == s2[i]) {
        dp[0][i] = 1;
      }
      else {
        dp[0][i] = 0;
      }
    }
    for(int i=0;i<s1.length();i++) { //dp[i][j]第一列，s1[i]和s2[0]相等就把dp[i][0]设为1，否则为0
      if(s1[i] == s2[0]) {
        dp[i][0] = 1;
      }
      else {
        dp[i][0] = 0;
      }
    }
    for(int i=1;i<s1.length();i++) {
      for(int j=1;j<s2.length();j++) {
        if(s1[i] == s2[j]) {
          dp[i][j] = dp[i-1][j-1] + 1; //关键
        }
        else {
          dp[i][j] = 0;
        }
      }
    }
    int m = 0;
    for(int i=0;i<s1.length();i++) {
      for(int j=0;j<s2.length();j++) {
        m = dp[i][j]>m ? dp[i][j] : m;
      }
    }
    cout<<m<<endl;
  }
}