C语言完全平方数算法有哪些

暴力法：遍历所有可能的完全平方数，判断是否等于给定的数。

#include <stdio.h>int isPerfectSquare(int num) {    for (int i = 1; i * i <= num; i++) {        if (i * i == num) {            return 1;        }    }    return 0;}int main() {    int num;    printf("Enter a number: ");    scanf("%d", &num);    if (isPerfectSquare(num)) {        printf("%d is a perfect square.\n", num);    } else {        printf("%d is not a perfect square.\n", num);    }    return 0;}

二分查找法：利用二分查找的思想，在范围内查找给定数的平方根，判断是否为完全平方数。

#include <stdio.h>int isPerfectSquare(int num) {    long left = 1, right = num;    while (left <= right) {        long mid = left + (right - left) / 2;        long square = mid * mid;        if (square == num) {            return 1;        } else if (square < num) {            left = mid + 1;        } else {            right = mid - 1;        }    }    return 0;}int main() {    int num;    printf("Enter a number: ");    scanf("%d", &num);    if (isPerfectSquare(num)) {        printf("%d is a perfect square.\n", num);    } else {        printf("%d is not a perfect square.\n", num);    }    return 0;}

这两种算法都可以判断一个数是否为完全平方数，第二种算法的效率更高一些。