Change the order of operation in case of the overflow

rsk0315 · rsk0315 · commit 42011962c40a · 2020-12-16T15:46:48.000+09:00
diff --git a/atcoder/math.hpp b/atcoder/math.hpp
@@ -82,7 +82,7 @@ std::pair<long long, long long> crt(const std::vector<long long>& r,
 long long floor_sum(long long n, long long m, long long a, long long b) {
     long long ans = 0;
     if (a >= m) {
-        ans += (n - 1) * n * (a / m) / 2;
+        ans += (n - 1) * n / 2 * (a / m);
         a %= m;
     }
     if (b >= m) {

Original file line number	Diff line number	Diff line change
`@@ -82,7 +82,7 @@ std::pair<long long, long long> crt(const std::vector<long long>& r,`
`82`	`82`	`long long floor_sum(long long n, long long m, long long a, long long b) {`
`83`	`83`	`long long ans = 0;`
`84`	`84`	`if (a >= m) {`
`85`		`- ans += (n - 1) * n * (a / m) / 2;`
	`85`	`+ ans += (n - 1) * n / 2 * (a / m);`
`86`	`86`	`a %= m;`
`87`	`87`	`}`
`88`	`88`	`if (b >= m) {`