第七周必做题。

07/Exercise01.c

@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <math.h>
+
+double f(double x);
+double S(double a, double b, int m);
+
+double f(double x) {
+    return pow(exp(1.0), -x*x);
+}
+
+double S(double a, double b, int m) {
+    double step =  (b-a) / m;
+    double ans = 0;
+    int i = 0;
+    for (i = 0; i < m; i++) {
+        ans += step * (f(a + step * i) + f(a + step * (i + 1))) / 2;
+    }
+    return ans;
+}
+
+int main() {
+    double a, b;
+    int m;
+    double bestResult;
+    double lowerBond, upperBond;
+    bestResult = S(-1, 1, 2000);
+    printf("The best result we get is %.10lf\n", bestResult);
+    lowerBond = ((int)(bestResult * 10000)) / 10000.0;
+    upperBond = lowerBond + 0.0001;
+    for (m = 1; m <= 2000; m++) {
+        if (S(-1, 1, m) >= lowerBond && S(-1,1,m) < upperBond) {
+            printf("Now the first m that satisfies the requirment is %d, the result is %.10lf.", m, S(-1,1,m));
+            break;
+        }
+    }
+    return 0;
+}

07/Exercise02.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+
+int main() {
+    int old, stand, lie;
+    for (old = 3; old < 97; old+=3) {
+        for (stand = 1; stand < 100 - old; stand++) {
+            lie = 100 - stand - old;
+            if ((lie*3 + stand*5 + old/3) == 100) {
+                printf("Stand: %d Lie %d Old: %d\n", stand, lie, old);
+            }
+        }
+    }
+    return 0;
+}