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题目

解题思路

话说我很喜欢数独欸

暴搜尝试一个地方可以填什么数

Code

#include <iostream>
#include <cstring>
#include <cstdio>
#include <string>

using namespace std;

string s;
int c, a[15][15], h, x[15][15], y[15][15], g[15][15];

int check(int x, int y) {
    
    //九宫格编号从左到右从上到下 1~9
	if (x <= 3) {
    
    
		if (y <= 3) return 1;
		if (y > 3 && y <= 6) return 2;
		return 3;
	}
	if (x > 3 && x <= 6) {
    
    
		if (y <= 3) return 4;
		if (y > 3 && y <= 6) return 5;
		return 6;
	}
	if (y <= 3) return 7;
	if (y > 3 && y <= 6) return 8;
	return 9;
} 

void dfs(int xx,int yy) {
    
    
	if (h) return;//是否找到过解
	if (xx > 9) {
    
    //找到解
		for (int i = 1; i <= 9; i++)
			for (int j = 1; j <= 9; j++)
				printf("%d", a[i][j]);
		h = 1;
		return;
	}
	if (a[xx][yy]) {
    
    //如果已有固定的数
		if (yy < 9)
			dfs(xx, yy + 1);
		else dfs(xx + 1, 1);
		return;
	}
	for (int i = 1; i <= 9; i++) {
    
    
		if (!x[xx][i] && !y[yy][i] && !g[check(xx, yy)][i]) {
    
    //尝试填数
			x[xx][i] = y[yy][i] = g[check(xx, yy)][i] = 1;
			a[xx][yy] = i;
			if (yy < 9)
				dfs(xx, yy + 1);
			else dfs(xx + 1, 1);
			a[xx][yy] = 0;
			x[xx][i] = y[yy][i] = g[check(xx, yy)][i] = 0;
		}
	}
}

int main() {
    
    
	cin>>s;
	while (s != "end") {
    
    
		h = 0;
		memset(a, 0, sizeof(a));
		memset(x, 0, sizeof(x));
		memset(y, 0, sizeof(y));
		memset(g, 0, sizeof(g));
		for (int i = 1; i <= 9; i++)
			for (int j = 1; j <= 9; j++)
				{
    
    
					c = (i - 1) * 9 + j;
					if (s[c - 1] >= '0' && s[c - 1] <= '9') {
    
    
						a[i][j] = s[c - 1] - '0';
						x[i][a[i][j]] = y[j][a[i][j]] = g[check(i, j)][a[i][j]] = 1;//记录行、列、九宫格
					}
				}
		dfs(1, 1);
		printf("\n");
		cin>>s;
	} 
}