杨氏矩阵查找(美团)

最新推荐文章于 2024-04-21 11:52:34 发布

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/*****************************************************
file: young_matrix.c
brief:find a key in the young matrix which keeps a increase order in row and col

2015.1.3   yejing   1.0   creat file
*****************************************************/

#include <stdio.h>
#include <stdlib.h>

/*
朴素杨氏矩阵查找
主要依赖其堆序性质，从左下角或者右上角开始
*/
int young_matrix_search_normal(int array[][4], int tgt){
	int tmp = array[0][3];
	int i = 0, j = 3;
	do{
		if(tgt == tmp){
			printf("%s:x = %d, y = %d \n",__func__, i + 1, j + 1);
			return 1;
		}
		else if(tgt < tmp && j > 0)
			tmp = array[i][--j];
		else if(tgt > tmp && i < 3)
			tmp = array[++i][j];
		else
			return 0;
	}while(1);
}
/*
二分杨氏矩阵查找
先计算中间点，比中间点小的查左上角矩阵，大的查另外三个矩阵
*/
int young_matrix_binary_search(int array[][4], int start_x, int start_y, int end_x, int end_y, int tgt){
	int middle_x, middle_y;
	middle_x = (start_x + end_x)/2;
	middle_y = (start_y + end_y)/2;
	int middle = array[middle_x][middle_y];
	if(tgt == middle){
		printf("%s:x = %d, y = %d \n",__func__, middle_x + 1, middle_y + 1);
		return 1;
	}else if(middle_x == start_x && middle_y == start_y){
		//printf("search failed, no key:%d \n", tgt);
		return 0;
	}
	else if(middle > tgt)
		young_matrix_binary_search(array, start_x, start_y, middle_x, middle_y, tgt);
	else if(middle < tgt){
		young_matrix_binary_search(array, middle_x, middle_y, end_x, end_y, tgt);
		young_matrix_binary_search(array, start_x, middle_y, middle_x, end_y, tgt);
		young_matrix_binary_search(array, middle_x, start_y, end_x, middle_y, tgt);
	}
}


int main(int argc, char* argv[]){
	int array[][4] = {
	{1, 4, 7, 10},
	{2, 5, 8, 11},
	{3, 6, 9, 12},
	{4, 7, 10, 13},
	};
	young_matrix_search_normal(array, 9);
	young_matrix_binary_search(array,0, 0, 3, 3, 9);
	return 1;
}