使用c语言,解决模拟退火解决n皇后问题,写出代码
时间: 2024-12-20 21:24:07 浏览: 8
在C语言中,使用模拟退火算法求解N皇后问题是常见的优化问题实例。下面是一个简单的示例代码,它实现了基本的模拟退火过程来寻找N皇后问题的一个解决方案:
```c
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// 检查在给定列和对角线位置上是否可以放置皇后
int isSafe(int row, int col, int N, int board[][N]) {
// 对角线上检查
for (int i = 0; i < row; ++i)
if (board[i][col] == 1 || abs(i - row) == abs(col - board[i][col]))
return 0;
return 1;
}
// 初始化棋盘状态
void initBoard(int N, int board[][N]) {
for (int i = 0; i < N; ++i)
for (int j = 0; j < N; ++j)
board[i][j] = 0;
}
// 交换两个皇后的位置
void swap(int row1, int col1, int row2, int col2, int board[][N]) {
int temp = board[row1][col1];
board[row1][col1] = board[row2][col2];
board[row2][col2] = temp;
}
// 扩展函数:模拟退火步骤
void simulatedAnnealing(int N, double initialTemp, double coolingRate, int maxIterations, int board[][N]) {
srand(time(0));
int currentEnergy = -999999; // 目前的状态能量
int bestRow[N], bestCol[N]; // 最佳皇后位置
while (initialTemp > 1e-6 && maxIterations--) {
int i = rand() % N;
int j = rand() % N;
if (isSafe(i, j, N, board)) {
swap(i, bestCol[i], j, bestCol[j], board);
int newEnergy = calculateEnergy(N, board); // 计算新状态的能量
double acceptanceProb = exp((currentEnergy - newEnergy) / initialTemp);
if (acceptanceProb > random()) { // 接受概率大于随机数,则接受新状态
currentEnergy = newEnergy;
for (int k = 0; k < N; ++k) {
bestRow[k] = i;
bestCol[k] = j;
}
} else { // 否则,尝试恢复旧状态
swap(i, j, bestRow[i], bestCol[i], board);
}
}
initialTemp *= coolingRate;
}
printf("\nSolution found with the following positions:\n");
for (int i = 0; i < N; ++i) {
printf("Q at (%d,%d)\n", i, bestCol[i]);
}
}
// 能量计算函数,这里假设每行、每列和每个对角线只有一个皇后时能量最小,计为-1,否则为0
int calculateEnergy(int N, int board[][N]) {
int energy = 0;
for (int i = 0; i < N; ++i)
for (int j = 0; j < N; ++j)
energy += (board[i][j] == 1 ? 1 : 0);
return energy;
}
int main() {
int N;
printf("Enter the size of the chessboard (N): ");
scanf("%d", &N);
int board[N][N];
simulatedAnnealing(N, 100, 0.95, 1000, board);
return 0;
}
```
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