Time: 68 ms (98.86%), Space: 40.4 MB (60.23%) - LeetHub

Author: JanaSabuj

random-pick-with-weight/random-pick-with-weight.cpp

@@ -0,0 +1,24 @@
+class Solution {
+    vector<int> cum;
+public:
+    
+    Solution(vector<int>& w) {
+        int prev = 0;        
+        for(auto x: w){
+            cum.push_back(x + prev);
+            prev = cum.back();
+        }                
+    }
+    
+    int pickIndex() {
+        int total = cum.back();
+        int val = rand() % total + 1;
+        return lower_bound(cum.begin(), cum.end(), val) - cum.begin();
+    }
+};
+
+/**
+ * Your Solution object will be instantiated and called as such:
+ * Solution* obj = new Solution(w);
+ * int param_1 = obj->pickIndex();
+ */