C++實現最長公共子序列和最長公共子串
阿新 • • 發佈:2019-02-11
// LCS.cpp : 定義控制檯應用程式的入口點。 // #include "stdafx.h" #include <string> #include <vector> #include <iostream> using namespace::std; int lcs(string str1, string str2, vector<vector<int>>& vec) { int len1 = str1.size(); int len2 = str2.size(); vector<vector<int>> c(len1 + 1, vector<int>(len2 + 1, 0)); for (int i = 0; i <= len1; i++) { for (int j = 0; j <= len2; j++) { if (i == 0 || j == 0) { c[i][j] = 0; } else if (str1[i - 1] == str2[j - 1]) { c[i][j] = c[i - 1][j - 1] + 1; vec[i][j] = 0; } else if (c[i - 1][j] >= c[i][j - 1]){ c[i][j] = c[i - 1][j]; vec[i][j] = 1; } else{ c[i][j] = c[i][j - 1]; vec[i][j] = 2; } } } return c[len1][len2]; } void print_lcs(vector<vector<int>>& vec, string str, int i, int j) { if (i == 0 || j == 0) { return; } if (vec[i][j] == 0) { print_lcs(vec, str, i - 1, j - 1); printf("%c", str[i - 1]); } else if (vec[i][j] == 1) { print_lcs(vec, str, i - 1, j); } else { print_lcs(vec, str, i, j - 1); } } int _tmain(int argc, _TCHAR* argv[]) { string str1 = "123456"; string str2 = "2456"; vector<vector<int>> vec(str1.size() + 1, vector<int>(str2.size() + 1, -1)); int result = lcs(str1, str2, vec); cout << "result = " << result << endl; print_lcs(vec, str1, str1.size(), str2.size()); getchar(); return 0; }
int lcs_2(string str1, string str2, vector<vector<int>>& vec) { int len1 = str1.size(); int len2 = str2.size(); int result = 0; //記錄最長公共子串長度 vector<vector<int>> c(len1 + 1, vector<int>(len2 + 1, 0)); for (int i = 0; i <= len1; i++) { for (int j = 0; j <= len2; j++) { if (i == 0 || j == 0) { c[i][j] = 0; } else if (str1[i - 1] == str2[j - 1]) { c[i][j] = c[i - 1][j - 1] + 1; vec[i][j] = 0; result = c[i][j] > result ? c[i][j] : result; } else { c[i][j] = 0; } } } return result; } void print_lcs(vector<vector<int>>& vec, string str, int i, int j) { if (i == 0 || j == 0) { return; } if (vec[i][j] == 0) { print_lcs(vec, str, i - 1, j - 1); printf("%c", str[i - 1]); } else if (vec[i][j] == 1) { print_lcs(vec, str, i - 1, j); } else { print_lcs(vec, str, i, j - 1); } } int _tmain(int argc, _TCHAR* argv[]) { string str1 = "123456"; string str2 = "14568"; vector<vector<int>> vec(str1.size() + 1, vector<int>(str2.size() + 1, -1)); int result = lcs_2(str1, str2, vec); cout << "result = " << result << endl; print_lcs(vec, str1, str1.size(), str2.size()); getchar(); return 0; }