Create 2152-minimum-number-of-lines-to-cover-points.js

Author: everthis

2152-minimum-number-of-lines-to-cover-points.js

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+/**
+ * @param {number[][]} points
+ * @return {number}
+ */
+const minimumLines = function(points) {
+  const n = points.length;
+  const connects = Array.from({ length: n }, () => Array(n).fill(0));
+  for(let i = 0; i < n; ++i) {
+      for(let j = i + 1; j < n; ++j) {
+          connects[i][j] = (1 << i) | (1 << j);
+          let dx = points[j][0] - points[i][0];
+          let dy = points[j][1] - points[i][1];
+          for(let k = j + 1; k < n; ++k) { // check if k will be on the line connecting i and j.
+              let dx2 = points[k][0] - points[i][0];
+              let dy2 = points[k][1] - points[i][1];
+              if (dx * dy2 == dy * dx2) {
+                  connects[i][j] |= (1 << k);
+              }
+          }
+      }
+  }
+  const dp = new Array(1<<n).fill(Infinity);
+  return helper(n, 0, dp, connects);
+};
+
+function helper(n, mask, dp, connects) {
+  if (dp[mask] == Infinity) {
+      let has = numOfOne(mask);
+      if (has == n) { // if all the points have been connected
+          dp[mask] = 0;
+      } else if (has >= n - 2) { // if only 2 points left
+          dp[mask] = 1;
+      } else { // if there are more than 2 points, try a line connecting first to second, third, ...
+          let i = 0;
+          for(let x = (1 << i); i < n; ++i, x <<= 1) {
+              if ((mask & x) == 0) {
+                  break;
+              }
+          }
+          for(let j = i + 1, x = (1 << j); j < n; ++j, x <<= 1) {
+              if ((mask & x) == 0) {
+                  let mask2 = mask | connects[i][j];
+                  dp[mask] = Math.min(dp[mask], 1 + helper(n, mask2, dp, connects));
+              }
+          }
+      }
+  }
+  return dp[mask];
+}
+
+function numOfOne(num) {
+  const str = (num >>> 0).toString(2)
+  let res = 0
+  for(let ch of str) {
+    if(ch === '1') res++
+  }
+  return res
+}