C语言判断三条边能否构成三角形

曾经终败给现在 2022-03-07 16:26 511阅读 0赞

**算法基础：**  
两边之和大于第三边，并且两边之差小于第三边时可构成三角形。

/*----------------------------------
    功能：判断三条边能否构成一个三角形
    输入示例：
    2
    3.1 4 5
    1 2 3
    输出示例：
    Yes
    No
    -----------------------------------
    Author: Zhang Kaizhou
    Date: 2019-3-17 13:03:17
    ----------------------------------*/
    #include <stdio.h>
    #include <stdlib.h>
    #include <math.h>
    
    typedef struct node{
        float a, b, c;
        int res;
        struct node * pnext;
    } Node;
    
    void judge_triangle(Node * p);
    void list_tail_insert(Node ** pphead, Node ** pptail, Node * p);
    void list_print(Node * phead);
    
    int main(){
        Node * phead = NULL, * ptail = NULL;
        int n, i;
        scanf("%d", &n);
        for(i = 0; i < n; i++){
            Node * pnew = (Node *)calloc(1, sizeof(Node));
            scanf("%f %f %f", &pnew->a, &pnew->b, &pnew->c);
            judge_triangle(pnew);
            list_tail_insert(&phead, &ptail, pnew);
        }
        list_print(phead);
    
        return 0;
    }
    
    void judge_triangle(Node * p){
        if(p->a + p->b > p->c && p->a + p->c > p->b && p->b + p->c > p->a &&
           fabs(p->a - p->b) < p->c && fabs(p->a - p->c) < p->b && fabs(p->b - p->c) < p->a){
            p->res = 1;
        }else{
            p->res = 0;
        }
        return;
    }
    
    void list_tail_insert(Node ** pphead, Node ** pptail, Node * p){
        if(* pphead == NULL){
            * pphead = p;
            * pptail = p;
        }else{
            (* pptail)->pnext = p;
            * pptail = p;
        }
        return;
    }
    
    void list_print(Node * phead){
        while(phead != NULL){
            if(phead->res == 1){
                printf("Yes\n");
            }else{
                printf("No\n");
            }
            phead = phead->pnext;
        }
        return;
    }