10.10: backtracking(부분수열의 합)

baekjoon/1182.js

@@ -0,0 +1,35 @@
+// 부분수열의 합 : 백트래킹, 브루트 포스
+const input = require("fs")
+  .readFileSync("/dev/stdin")
+  .toString()
+  .trim()
+  .split("\n")
+  .map((v) => v.split(" ").map((v) => parseInt(v, 10)));
+const [n, s] = input.shift();
+const arr = input.shift();
+const visited = [];
+let answer = 0;
+let total = 0;
+
+function isIncluded(num) {
+  for (let i = 0; i < visited.length; i++) if (visited[i] === num) return true;
+  return false;
+}
+
+function recur(depth = 0) {
+  if (total === s && depth > 0) answer++;
+  if (depth === n) return;
+
+  for (let i = 0; i < n; i++) {
+    if (isIncluded(i) || visited[visited.length - 1] >= i) continue;
+    visited.push(i);
+    total += arr[i];
+    recur(depth + 1);
+    visited.pop();
+    total -= arr[i];
+  }
+}
+
+recur();
+
+console.log(answer);