动态规划--LCS

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/************************************************************* * file:lcs.c * brief:基于动态规划，求两个字符串的最长公共子序列 * yejing@2015.2.3    1.0      creat *************************************************************/ #include <stdio.h>#include <stdlib.h>#include <assert.h>#include <string.h>#define MATRIX_MLEN 128typedef enum{DIR_UP,DIR_LEFT,DIR_UP_LEFT}DIR_t;void generate_lcs_matrix(char* str1, int len1, char* str2, int len2,  int lcs_matrix[][MATRIX_MLEN], int dir_matrix[][MATRIX_MLEN]){int i = 0, j = 0;if(len1 > MATRIX_MLEN || len2 > MATRIX_MLEN)assert(0);for(i = 0; i <= len1; ++i)lcs_matrix[i][0] = 0;for(j = 0; j <= len2; ++j)lcs_matrix[0][j] = 0;for(i = 1; i <= len1; ++i){for(j = 1; j <= len2; ++j){if(str1[i - 1] == str2[j - 1]){lcs_matrix[i][j] = lcs_matrix[i - 1][j - 1] + 1;dir_matrix[i][j] = DIR_UP_LEFT;}else if(lcs_matrix[i - 1][j] >= lcs_matrix[i][j - 1]){dir_matrix[i][j] = DIR_UP;lcs_matrix[i][j] = lcs_matrix[i - 1][j];}else{dir_matrix[i][j] = DIR_LEFT;lcs_matrix[i][j] = lcs_matrix[i][j - 1];}}}return;}void show_lcs(int dir_matrix[][MATRIX_MLEN], char* str1, int i, int j){if(i == 0 || j == 0)return;if(dir_matrix[i][j] == DIR_UP_LEFT){show_lcs(dir_matrix, str1, i - 1, j - 1);printf("%c ", str1[i - 1]);}else if(dir_matrix[i][j] == DIR_LEFT){show_lcs(dir_matrix, str1, i, j - 1);}else{show_lcs(dir_matrix, str1, i - 1, j);}return;}int main(int argc, char* argv[]){char* str1 = "aqswdefrgthyjukil";char* str2 = "azsxdcfvgbhnjmkl";int lcs_matrix[MATRIX_MLEN][MATRIX_MLEN];int dir_matrix[MATRIX_MLEN][MATRIX_MLEN];generate_lcs_matrix(str1, strlen(str1), str2, strlen(str2), lcs_matrix, dir_matrix);show_lcs(dir_matrix, str1, strlen(str1), strlen(str2));printf("\n");return 1;}
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