C语言蓝桥杯刷题：最短路

题目链接

#include<stdio.h>

#define SIZE 20  
#define INF 999;  

int map[SIZE][SIZE];  //邻接矩阵存储 
int len[SIZE];  	//len[i]表示源点到i这个点的距离 
int visit[SIZE];  //节点是否被访问 
int n = 19,m;

int dijkstra(int from, int to) {	//从源点到目标点 

	int i;

	for (i = 1; i <= n; i++) {	//初始化 
		visit[i] = 0;	//一开始每个点都没被访问 
		len[i] = map[from][i];	//先假设源点到其他点的距离 
	}

	int j;
	for (i = 1; i < n; ++i) {	//对除源点的每一个点进行最短计算 
		int min = INF;  //记录最小len[i] 
		int pos;  //记录小len[i] 的点 

		for (j = 1; j <= n; ++j) {
			if (!visit[j] && min > len[j]) {
				pos = j;
				min = len[j];
			}
		}
		visit[pos] = 1;

		for (j = 1; j <= n; ++j) {
			if (!visit[j] && (len[j] > (len[pos] + map[pos][j]))) { //如果j节点没有被访问过&&j节点到源节点的最短路径>pos节点到源节点的最短路径+pos节点到j节点的路径  
				len[j] = len[pos] + map[pos][j];	//更新j节点到源节点的最短路径	
			}
		}
	}

	return len[to];
}


int main() {

	int i, j;

	

	for (i = 1; i <= n; ++i) {	//设一开始每个点都不可达 
		for (j = 1; j <= n; ++j) {
			map[i][j] = INF;
		}
	}

	

		//初始化
	map[1][1] = 0;
	map[1][2] = 2;
	map[1][3] = 1;
	map[1][4] = 1;
	map[1][5] = 1;

	map[2][2] = 0;//求最短路径就没必要再写arr[2][1]这种回头路了
	map[2][7] = 1;
	map[2][10] = 2;

	map[3][3] = 0;
	map[3][4] = 3;
	map[3][6] = 3;
	map[3][7] = 3;

	map[4][4] = 0;
	map[4][5] = 1;
	map[4][7] = 2;
	map[4][8] = 1;
	map[4][9] = 2;

	map[5][5] = 0;
	map[5][8] = 1;
	map[5][9] = 3;

	map[6][6] = 0;
	map[6][7] = 1;
	map[6][9] = 1;

	map[7][7] = 0;
	map[7][9] = 3;

	map[8][8] = 0;
	map[8][9] = 1;
	map[8][12] = 2;

	map[9][9] = 0;
	map[9][13] = 3;

	map[10][10] = 0;
	map[10][19] = 2;

	map[11][11] = 0;
	map[11][12] = 3;
	map[11][14] = 1;
	map[11][16] = 2;

	map[12][12] = 0;
	map[12][13] = 1;
	map[12][18] = 1;

	map[13][13] = 0;
	map[13][14] = 2;
	map[13][17] = 1;
	map[13][19] = 1;

	map[14][14] = 0;
	map[14][16] = 1;

	map[15][15] = 0;
	map[15][16] = 1;
	map[15][17] = 1;
	map[15][18] = 3;

	map[16][16] = 0;

	map[17][17] = 0;

	map[18][18] = 0;
	map[18][19] = 1;

	map[19][19] = 0;

	
	int temp = INF;
	for (i = 1; i <= n; i++) {
		for (j = 1; j <= n; j++) {
			if (map[i][j] == temp)
				map[i][j] = map[j][i];
		}
	}

	printf("%d", dijkstra(1, 19));

	return 0;
}