在C言语编程中，我们常常碰到各种复杂的算法成绩。这些算法可能是排序、查抄、字符串处理等。而在这其中，“大年夜A”算法（平日指的是A*查抄算法）是一个非常有效的东西。本文将深刻剖析“大年夜A”算法的奥秘，并展示如何在一招中轻松控制它。
A*算法是一种启发式查抄算法，它结合了最佳优先查抄跟Dijkstra算法的长处。它的核心头脑是评价每个节点的“总价值”，这个总价值由两部分构成：现实本钱跟启发式估计本钱。
A*算法会优先抉择总价值最小的节点停止扩大年夜，从而找到从出发点到目标的最短道路。
下面是一个简单的A*算法的C言语实现示例：
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#define MAX_NODES 1000
typedef struct {
int x, y;
} Point;
typedef struct {
Point point;
int g, h, f;
} Node;
Node openList[MAX_NODES];
Node closedList[MAX_NODES];
int openListSize = 0;
int closedListSize = 0;
int heuristic(Point a, Point b) {
return abs(a.x - b.x) + abs(a.y - b.y);
}
int findNode(Point p) {
for (int i = 0; i < openListSize; i++) {
if (openList[i].point.x == p.x && openList[i].point.y == p.y) {
return i;
}
}
return -1;
}
void addOpenList(Node node) {
openList[openListSize++] = node;
}
void addClosedList(Node node) {
closedList[closedListSize++] = node;
}
void removeOpenList(int index) {
for (int i = index; i < openListSize - 1; i++) {
openList[i] = openList[i + 1];
}
openListSize--;
}
int main() {
// 初始化出发点跟起点
Point start = {0, 0};
Point end = {5, 5};
// 增加出发点到开放列表
Node startNode = {start, 0, heuristic(start, end), 0};
addOpenList(startNode);
while (openListSize > 0) {
// 找到总价值最小的节点
int minIndex = 0;
for (int i = 1; i < openListSize; i++) {
if (openList[i].f < openList[minIndex].f) {
minIndex = i;
}
}
// 获取以后节点
Node currentNode = openList[minIndex];
removeOpenList(minIndex);
addClosedList(currentNode);
// 假如达到起点，则结束
if (currentNode.point.x == end.x && currentNode.point.y == end.y) {
break;
}
// 扩小节点
Point neighbor;
neighbor.x = currentNode.point.x - 1;
neighbor.y = currentNode.point.y;
if (neighbor.x >= 0 && neighbor.y >= 0 && neighbor.x < 5 && neighbor.y < 5) {
int index = findNode(neighbor);
if (index == -1) {
Node neighborNode = {neighbor, currentNode.g + 1, heuristic(neighbor, end), currentNode.g + 1 + heuristic(neighbor, end)};
addOpenList(neighborNode);
} else {
if (currentNode.g + 1 < openList[index].g) {
openList[index].g = currentNode.g + 1;
openList[index].f = currentNode.g + 1 + heuristic(neighbor, end);
}
}
}
neighbor.x = currentNode.point.x + 1;
neighbor.y = currentNode.point.y;
if (neighbor.x >= 0 && neighbor.y >= 0 && neighbor.x < 5 && neighbor.y < 5) {
int index = findNode(neighbor);
if (index == -1) {
Node neighborNode = {neighbor, currentNode.g + 1, heuristic(neighbor, end), currentNode.g + 1 + heuristic(neighbor, end)};
addOpenList(neighborNode);
} else {
if (currentNode.g + 1 < openList[index].g) {
openList[index].g = currentNode.g + 1;
openList[index].f = currentNode.g + 1 + heuristic(neighbor, end);
}
}
}
neighbor.x = currentNode.point.x;
neighbor.y = currentNode.point.y - 1;
if (neighbor.x >= 0 && neighbor.y >= 0 && neighbor.x < 5 && neighbor.y < 5) {
int index = findNode(neighbor);
if (index == -1) {
Node neighborNode = {neighbor, currentNode.g + 1, heuristic(neighbor, end), currentNode.g + 1 + heuristic(neighbor, end)};
addOpenList(neighborNode);
} else {
if (currentNode.g + 1 < openList[index].g) {
openList[index].g = currentNode.g + 1;
openList[index].f = currentNode.g + 1 + heuristic(neighbor, end);
}
}
}
neighbor.x = currentNode.point.x;
neighbor.y = currentNode.point.y + 1;
if (neighbor.x >= 0 && neighbor.y >= 0 && neighbor.x < 5 && neighbor.y < 5) {
int index = findNode(neighbor);
if (index == -1) {
Node neighborNode = {neighbor, currentNode.g + 1, heuristic(neighbor, end), currentNode.g + 1 + heuristic(neighbor, end)};
addOpenList(neighborNode);
} else {
if (currentNode.g + 1 < openList[index].g) {
openList[index].g = currentNode.g + 1;
openList[index].f = currentNode.g + 1 + heuristic(neighbor, end);
}
}
}
}
return 0;
}
经由过程本文的介绍，信赖你曾经对A*算法有了深刻的懂得。A*算法是一种非常实用的查抄算法，它可能利用于各种场景，如道路打算、迷宫求解等。控制A*算法，可能帮助你轻松处理很多复杂的编程成绩。