jump game

Author: ssfxz

45.cpp

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    int jump(vector<int>& nums) {
+        int len = nums.size();
+        
+        int ret = 0;//当前跳数  
+        int last = 0;//上一跳可达最远距离  
+        int curr = 0;//当前一跳可达最远距  
+        
+        for (int i = 0; i < len; ++i) {  
+            //无法向前继跳直接返回  
+//          if(i > curr){  
+//              return -1;  
+//          }  
+            //需要进行下次跳跃，则更新last和当执行的跳数ret
+            if (i > last) {  
+                last = curr;  
+                ++ret;  
+            }  
+            //记录当前可达的最远点
+            curr = max(curr, i + nums[i]);  
+        }
+        
+        return ret;
+    }
+};

55.cpp

@@ -1,24 +1,11 @@
 class Solution {
 public:
     bool canJump(vector<int>& nums) {
-        int step = nums[0];
         int len = nums.size();
-        
-        for(int i = 0; i < len; i++)
-        {
-            if(step-- <= 0)
-                return false;
-            
-            if(step < nums[i])
-            {  
-                step = nums[i];  
-            }
-            
-            if(i + 1  + step >= len)
-            {
-                return true;
-            }
+        int reach = 0;
+        for(int i = 0; i <= reach && i < len; ++i) {
+            reach = max(reach, i + nums[i]);
         }
-        return false;
+        return reach >= len - 1;
     }
 };