diff --git a/2780. Minimum Index of a Valid Split b/2780. Minimum Index of a Valid Split
new file mode 100644
index 0000000..bee9be7
--- /dev/null
+++ b/2780. Minimum Index of a Valid Split	
@@ -0,0 +1,22 @@
+struct Solution {
+  int minimumIndex(vector<int>& nums) {
+    int dom=1;
+    uint dom_count=1;
+    for (auto& i:nums) {  // find dom
+      if (dom_count==0) { ++dom_count; dom = i; }
+      else dom_count += i==dom ? 1 : -1;
+    }
+    dom_count=0;  // re-use as proper count
+    for (auto& i:nums) if (i==dom) ++dom_count;
+    uint doms=0;
+    // cout << dom << endl;
+    auto it=nums.begin();
+    uint n=nums.size();
+    for (uint i=1, j=n-1; i<=n; ++i, --j, ++it) {
+      if (*it==dom) { ++doms; --dom_count; }
+      // cout << doms << "  " << dom_count << endl;
+      if (doms*2>i and dom_count*2>j) return i-1;
+    }
+    return -1;
+  }
+};