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public/c/ch1/compareall.c

@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include <time.h>
+// 函数声明
+long long sum_leijia(long long a, long long b);
+long long sum_gaosi(long long a, long long b);
+
+int main() {
+    clock_t before, middle, after;
+    long long a = 1LL, b = 100000000LL;
+    long long result1 = 0LL, result2 = 0LL;     
+    before = clock();    
+    result1 = sum_leijia(a, b);
+    middle = clock();    
+    printf("累加计算结果: %lld, 所用时间: %lf 毫秒\n", result1, (double)(middle - before) / CLOCKS_PER_SEC * 1000);
+    
+    // 计算公式方式的和并计时
+    result2 = sum_gaosi(a, b);
+    after = clock();    
+    printf("高斯求和结果: %lld, 所用时间: %lf 毫秒\n", result2, (double)(after - middle) / CLOCKS_PER_SEC * 1000);    
+
+    return 0;
+} 
+long long sum_leijia(long long a, long long b) {
+    long long sum = 0LL;
+    for (long long i = a; i <= b; i++) {
+        sum += i;
+    }
+    return sum;
+}
+ 
+long long sum_gaosi(long long a, long long b) {
+    return (a + b) * (b - a + 1) / 2;
+}